1. Field of the Invention
The present invention relates to novel 2-halomethyl-5-vinyl-1,3,4-oxadiazole compounds.
2. Brief Discussion of the Prior Art
Compounds capable of being decomposed upon exposure to light to form free radicals (free radical-generating agents) are well known in the field of graphic arts. They are widely used as photo-polymerization initiators in photo-polymerizable compositions, as a light-activatable agents in free radical photographic compositions, and as a photo-initiators for the reaction catalyzed by an acid generated by light. Various light-sensitive materials useful in image-forming systems such as printing, copying, and the like are prepared using such free radical-generating agents.
Organic halogen compounds release halogen free radicals when exposed to light, and, hence, they are useful as photo-initiators. As this type of organic halogen compounds, carbon tetrabromide, iodoform, tribromoacetophenone, etc., are typical and have widely been used. However, these free radical-generating agents have the defect that they are only decomposed by light of considerably limited wavelength region. That is, they respond to light in ultraviolet region wavelength which is shorter than the main wavelength of light emitted from ordinarily used light sources. Therefore, these compounds fail to effectively utilize light in near ultraviolet to visible region emitted from such light sources, thus, being poor in free radical-generating ability.